I'd start by either replacing the coax or putting dummy load
at the antenna end - all symptoms sound like a discontinuity
in the coas or connectors in spite of newness.
You could even just run twisted pair to replace the coax for
a quick verification that there is resonance even at a little
higher SWR.
It's almost always the electro-mechanical interface that fails
in my experience in things electronid.
73
Barry, W5GN
-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces@contesting.com] On Behalf Of
Herbert Schoenbohm
Sent: Wednesday, October 28, 2015 12:12 PM
To: towertalk@contesting.com
Subject: Re: [TowerTalk] Strange happening with 10 Meter Beam
John, The the problem was neither VSWR (very low) or Beam Direction (any
direction) even on the ground no signals were apparent except very very weak
ones were heard on ten in any direction. It appeared that a
dummy load was at the end of the feed line. The beam is one the
ground at 10 feet and the insulator cup were changed and the beta rods
installed. Immediately the signals started to come in and the rig came to
life on 10 meters. It appears the cups were acting more like a resistive
element and took out the signals but provided a good load for VSWR
measurements. I installed the beta rods which the manual said are
36 inches long....but no where in the book does it give me the distance from
the Driven Element for the shorting bar on the boom and I looked at every
page....... The manual just refers to it as "L" but does not say the
distance of "L".....Do you have nay idea?.\
Herb, KV4FZ
On 10/28/2015 12:39 PM, john@kk9a.com wrote:
Low SWR is not a bad thing. My homebrew 6el 10m beams have 1.1:1 SWR
28-29 MHz and they work very well. Does the SWR increase outside the 10m
band?
Is the antenna pointing the correct direction?
John KK9A
To: towertalk@contesting.com, Yuri <n2tta@yahoo.com>
Subject: [TowerTalk] Strange happening with 10 Meter Beam
From: Herbert Schoenbohm <herbert.schoenbohm@gmail.com>
Date: Wed, 28 Oct 2015 09:30:21 -0400
For the CQ WW I put up a 5 Element HyGain 10 meter beam(LJ-105CA) I
double and triple checked all the element lengths and the VSWR is so
low across the band it really excited me. It also scares me a bit as
up in the air the VSWR is never above 1.3 to 1 from 28.0 to 29.5. The
problem is that signals are very weak on non existent when compared to
my 3 element quad at 80 feet which was the only antenna that worked on
ten during the contest and after.. ( The yagi is one a separate tower
at 50 feet)
Here is what I have on it.
New piece of LMR-400 with good connectors fed directly to the
insulated (Hy Gain cup type) director. The beta rods were missing so I
use the direct feed to each director. (OWA type matching idea) I moved
the first director slightly closer to the driven element to obtain the
correct match at 28.4 Mhz Everything looks good but the 10 meter
antenna is about as good as a dummy load.
I have been building yagi's for over 50 years and have never had such
a strange problem. Even a beam with half the driven element missing
after a hurricane could hear something but what I have up can't.
Before I take it down I ask if anyone else had experiences with this
problem. It must be something very simple but I have checked
everything I can think of and still no joy here.
Please let me know
Herb Schoenbohm, KV4FZ
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